LEHER OF TRANSMITTAL. 



U. S. Department of Agriculture, 



Bureau of Plant Industry, 



Office of the Chief, 

 WasMngton, D. C, February 6, 1911. 



Sir: I have the honor to transmit herewith and to recommend for 

 pubhcation as Bulletin No. 213 of the special series of this Bureau 

 the accompanying technical paper by Dr. Erwin F. Smith, Miss 

 Nellie A. Brown, and Dr. C. O. Townsend, entitled "Crown-Gall of 

 Plants: Its Cause and Remedy." 



This paper deals with an infectious disease of fruit trees and many 

 other economic plants wliich, because of its infectious character, has 

 spread to many parts of the United States. It is known to occur 

 also in Europe and Africa. 



The importance of this disease is evident from the frequency of 

 appearance of references to it and the amount of literature already 

 published regarding it. Various theories have been advanced as to 

 its cause, many of these by men of high standing in pathological 

 work, but none have been able to establish their theories conclu- 

 sively. The disease has been ascribed to frost injuries, to fungi, to 

 slime molds, and to various small animals found infesting the older 

 galls. By practical orchardists and by most pathologists crown-gall 

 is generally regarded as a dangerous and destructive disease; by 

 some others it has been considered nonparasitic and of little economic 

 importance. 



The investigations here reported upon have covered a period of 

 six years, during which the nature of the disease has been determined, 

 its cause discovered, and its broadly infectious character established 

 through hundreds of carefully conducted experiments. Its ready 

 commvmicability by inoculation from plants of one natural family to 

 another is thoroughly established and indicates its importance to the 

 farmer and the horticulturist. 



As the problems involved are varied and important, with very 

 practical bearing on the production of a wide range of crop plants, 

 it is important that the well-established evidence accumulated in 



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